1. Field of the Invention
This invention relates to pre-acting retractable extending fire sprinklers.
2. Background Information
Fire protection sprinklers may be operated individually, e.g. by a self-contained thermally sensitive element, or as part of a deluge system in which fire retardant fluid flows through a number of open sprinklers, essentially simultaneously. Fire retardant fluids may include natural water or appropriate mixtures of natural water and one or more additives to enhance fire-fighting properties of a fire protection system.
Fire protection sprinklers generally include a body with an outlet, an inlet connectable to a source of fire retardant fluid under pressure, and a deflector supported by the body in a position opposing the outlet for distribution of the fire retardant fluid over a predetermined area to be protected from fire. Individual fire protection sprinklers may be automatically or non-automatically operating. In the case of automatically operating fire protection sprinklers, the outlet is typically secured in the normally closed or sealed position by a cap. The cap is held in place by a thermally-sensitive element which is released when its temperature is elevated to within a prescribed range, e.g. by the heat from a fire. In some cases, sprinklers are not permanently positioned in their spraying position, but are installed above or behind a cover that conceals the sprinkler for aesthetic reasons, or to prevent the sprinkler from interfering with the function of the chamber such as in an anechoic chamber. In such cases, the sprinkler is retracted from its spraying position when not in use, and telescopes to its spraying position either automatically or as directed by a control system.
Telescoping pipes have been used in fire sprinkler systems. U.S. Pat. No. 5,160,174 to Thompson shows telescoping pipes and applications for such pipes in fire sprinkler systems.
U.S. Pat. Nos. 5,921,322 and 6,216,963 relate to a hydraulic device for regulating the speed of deployment of sprinkler heads in preactive sprinkler systems. These prior art sprinklers do not disclose a mechanism to retract the sprinkler head. In the prior art systems, a sprinkler head is installed at one end of an inner conduit. The inner conduit fits inside an outer conduit as a position fits in a cylinder. There is an annular space between the inner and outer conduits. This annular space is bounded by slidable seals at each end. When a high-pressure fluid is applied to the inner conduit, the piston telescopes out of the outer conduit compressing the annular space between the cylinders. The prior art teaches that the fluid in the annular space is released either into the fire extinguishing media, to the outside of the outer conduit through a series of bleeder holes that can be varied in size to control the rate of travel of the piston.
Telescoping and retracting sprinkler systems have been used in irrigation systems. For example, U.S. Pat. No. 4,254,913 to Georgicv shows a retractable spray head for an irrigation system. U.S. Pat. No. 4,749,127 shows telescoping snow making apparatus that includes a telescoping and retracting spray head.
These applications do not show a retracting telescoping fire sprinkler.